Convective assembly of linear gold nanoparticle arrays at the micron scale for surface enhanced Raman scattering

A convective assembly technique at the micron scale analogous to the writing action of a “pipette pen” has been developed for the linear assembly of gold nanoparticle strips with micron scale width and millimeter scale length for surface enhanced Raman scattering (SERS). The arrays with interparticle gaps smaller than 3 nm are hexagonally stacked in the vicinity of the pipette tip. Variable numbers of stacked layers and clean surfaces of the assembled nanoparticles are obtained by optimizing the velocity of the pipette tip. The SERS properties of the assembled nanoparticle arrays rely on their stacking number and surface cleanliness.